Strong coherent interaction of Nd3+-Nd3+ pair ions in CaF2 crystal

Academic Article

Abstract

  • Excited Kramers fine level splittings of Nd3+ pair (M) and quartet (N) clusters in CaF2 crystal have been found and investigated by using absorption spectroscopy and accumulated photon echo (APE) techniques. Absorption spectra on the 4I9/2→4G5/2 transition between Kramers states split into four lines with overall splitting approximately 5 cm-1 (T = 9 K, NdF3 concentration 0.1, 0.3 and 1 wt%). At the picosecond laser excitation of the M- and N-centers on the same transition the APE kinetics was observed to be strongly modulated with multiple coherent beatings on pico- and nano-second time scale. Fast Fourier Transform (FFT) of the APE kinetics decay shows that nearest-neighbour absorption lines splittings 0.9, 1.5 and 2.1 cm-1 (M-center) are clearly defined in FFT spectrum. Theoretical study revealed that in general case the electrostatic interionic coupling lifts completely the eightfold degeneracy of the excited level of a pair of similar ions. The selection rules for the forced electric-dipole, magnetic dipole and quadrupole intermultiplet transitions are stated. It is suggested that in the case of Nd3+-Nd3+ pair in CaF2 (M-center), the strong quadrupole-quadrupole coupling is responsible for the fine splitting of the excited 4I9/2×4G5/2 levels and leads to delocalization of the optical electrons within ion pair.
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    Digital Object Identifier (doi)

    Author List

  • Basiev TT; Fedorov VV; Karasik AY; Pukhov KK
  • Start Page

  • 189
  • End Page

  • 197
  • Volume

  • 81
  • Issue

  • 3